Well tools, such as bridge plugs, packers and cement retainers, have been used for setting in earthen wells to seal well casings. Prior art well tools, such as bridge plugs, packers and retainers, typically each include a mandrel which provides a central member and which defines a longitudinal axis of the respective bridge plug, packer or retainer. The mandrel may be a tubular member which provides a fluid flow passage through the mandrel, but in the case of a bridge plug an interior passage through the bridge plug is sealed. In the prior art, an upper and lower sleeve are concentrically mounted around opposite ends the mandrel. In one conventional arrangement, the lower sleeve is fixedly mounted to the lower end of the mandrel and the upper sleeve is slidably moveable over the mandrel for moving toward the lower sleeve to set the respective well tool within a well casing. Disposed around the exterior of the mandrel and between the upper and lower sleeves are conically shaped elements and an elastomeric seal element, with the seal element located between the two conical elements. Slips are slidably disposed on opposite ends of the conical elements. The slips are typically defined by separate segments which are disposed around an outer circumference of a respective one of the conical elements. The slip segments have serrated outer surfaces which define grip teeth, the crests of which will cut into the casing disposed in a well to secure the well tool to the casing. The inner surfaces of the slips respective ones of the slip segments together define frusto-conical shaped inner surfaces which slidably engage mating frusto-conically shaped outer surfaces of the two conical elements, such that when the upper and lower sleeves are pushed toward one another as the well tool is being set, the slips are pushed outward and wedged between the conical elements and the casing. When the well tool is set, the seal element will be squeezed between the ends of the two conical elements to sealingly engage between the outer surface of the mandrel and the casing.
Prior art well tools, such as bridge plugs, packers and retainers, have typically been set by rigidly securing the upper end of the mandrel to a setting tool. The setting tool typically includes a setting sleeve which extends around the mandrel and engages the upper sleeve. As the setting tool is operated, the setting sleeve will push downward against the upper sleeve as the upper end of the mandrel is held in place. Preferably, the lower sleeve is fixedly mounted to the lower end of the mandrel and the upper sleeve is slidably moveable over the mandrel for moving toward the lower sleeve to set the well tool within a well casing. The setting sleeve of the setting tool will operate to stroke downward and push the upper sleeve toward the lower sleeve which is fixed in relation to the mandrel. The upper sleeve will then move downward toward lower sleeve, pushing the slips over the conical elements and pressing the elastomeric seal element between ends of the two conical elements to set the well tool within a well casing. During setting of the well tool, a shear pin will be sheared to release the setting tool from the set well tool so that the setting tool may be retrieved from the well and be redressed for use to set other well tools.